A conventional reservoir tank used in a vehicle includes a main portion mounted on a vehicle, a storage chamber disposed on the main portion for storing operating fluid, a vertically movable float disposed in the storage chamber and a switch device which is operated by the vertical movement of the float. The storage chamber is surrounded by side walls, a ceiling portion and a bottom portion.
In this conventional reservoir tank, when a predetermined quantity of operating fluid is stored in the storage chamber, the float is positioned at a position corresponding to the OFF position of the switch device. As the quantity of operating fluid in the storage chamber is reduced, the level of the fluid falls and the float descends. When the level of the operating fluid falls to a level causing the float to descend to a position corresponding to the ON level of the switch device, the switch device changes from the OFF position to the ON position, thereby causing an idiot light in the vehicle, for example, to be turned on.
With the conventional reservoir tank installed on a vehicle, when the brake is operated while the vehicle is traveling, the level of the operating fluid inclines as the operating fluid moves to one side of the reservoir tank because of the inertia force. When the operating fluid level is inclined to a rather significant extent because of the shifting of the operating fluid, the float may have a tendency to move downward to the ON position of the switch device. When the float moves downward to the ON position of the switch device, the switch device will change to the ON position and cause activation of the idiot light, even though there is a sufficient quantity of operating fluid in the reservoir tank. Thus, this conventional reservoir tank is liable in some instances to provide an inaccurate indication of the quantity or level of operating fluid.
In light of the foregoing, a need exists for a reservoir tank which provides a more accurate indication of the level or quantity of operating fluid within the reservoir tank in certain operating conditions of the vehicle.
A need also exists for a reservoir tank which is not as susceptible to variations in the operating conditions of the vehicle for purposes of providing an indication of the quantity of operating fluid in the reservoir tank.